1. Field of the Invention
The invention relates to a conveyor roller and to a conveyor path comprising such a conveyor roller.
2. Description of the Related Art
Roller conveyors with rollers exist in the prior art. These roller conveyors are used, for example, in rack storage systems, wherein a rack can have a plurality of roller conveyors arranged above and alongside one another. A plurality of pallets with goods can be mounted one behind the other on a roller conveyor, these pallets running on the rollers.
The roller conveyors are generally loaded either from one side and unloaded from the other side, so that the goods that pass onto the roller conveyors first are also unloaded again first therefrom. These rack storage systems are called first-in/first-out storage systems or FIFO storage systems. Some of these FIFO roller conveyors have an inclination which slopes from the loading point to the unloading point, so that pallets located on the roller conveyor are conveyed in the direction of the unloading point by gravitational force.
In another alternative, the roller conveyors are loaded from one side and unloaded from the same side, so that the goods that pass onto the roller conveyors last are unloaded first therefrom. These rack storage systems are called last-in/first-out storage systems or LIFO storage systems. Some of these storage systems also have an inclination in the direction of the loading or unloading point. When loading a further new pallet, for example by means of a forklift truck, the pallets that are already located on the roller conveyor are pushed rearward by the new pallet counter to the inclination. Moreover, this inclination has the effect that the pallets located on the roller conveyor always line up at the unloading point following the gravitational force.
In order to brake the speed of the pallets in the roller conveyors, the rollers of the conveyor paths are in part provided with brakes via which the speed of the rollers, and hence that of the pallets, can be retarded. It can thereby be prevented that the pallets run against one another at excessively high speed.
In some constructions, eddy-current brakes are used for this. Such a device for braking individual rollers of roller tracks is described in DE 7300091 U. A further construction is described in EP 1 243 528 A1.
Moreover, mechanical centrifugal brakes can be used, for example, in which the brake pads of the brakes are only contacted with corresponding braking surfaces at a specific rotational speed and are then pushed more strongly against the braking surfaces when the rotational speed increases due to the centrifugal force. Thus, it is ensured that the rollers can rotate in a non-retarded manner at a low speed. For higher speeds, an ever greater braking force is provided, so that exceeding of specific speeds can be prevented. A braking roller of that type is described in DE 202 12 979 U1, for example.
Retarded rollers of that type can be damaged or destroyed in particular in the case of LIFO conveyors, for example if pallets are pushed, for example by means of a forklift truck, at excessively high speed and with great pushing force onto the roller conveyors counter to the inclination of the conveyor path. In this case, the centrifugal brakes are activated and the pallets are pushed against the braking force by the forklift truck with great force. Since it is difficult to design the rollers and the included braking devices in a sufficiently stable way with reasonable economic outlay, the rollers can be damaged thereby. As a result, additional repair and maintenance costs may arise. To solve this problem, EP 1 847 485 A1 suggests providing freewheel in the braking roller, so that the braking effect of the described centrifugal brake is only provided in one direction of rotation.
It is the object of the invention to provide a compact conveyor roller and a conveyor path comprising at least one such conveyor roller, which can be produced in a cost-effective manner, which have a long service life and require low maintenance and/or repair costs during their service life.